Electrically driven compressors and methods for circulating lubrication oil through the same

ABSTRACT

An oil storage area ( 45   a ) is defined on the bottom of a motor chamber ( 45 ) of a scroll compressor ( 1 ). An oil transfer route ( 4   a ) is defined in the portion of a center housing ( 4 ) that corresponds to the storage area ( 45   a ). Lubricating oil L is separated from the discharged, compressed refrigerant by an oil separator ( 80 ) and the lubricating oil L is supplied to the rear side of a movable scroll ( 20 ) due to a pressure differential within the compressor ( 1 ). After lubricating slide contact portions of scroll walls ( 28, 30 ) of the fixed and movable scrolls ( 2, 20 ), the lubricating oil L is temporarily stored in the storage area ( 45   a ) and then is transferred due to a refrigerant pressure differential to the suction-side of a compression mechanism ( 21 ) via the oil transfer route ( 4   a ). The lubricating oil L is then transferred to the oil separator ( 80 ) together with the compressed refrigerant that is discharged from a compression chamber ( 32 ) of the compression mechanism ( 21 ). Thus, the lubricating oil L contained in the discharged, compressed refrigerant can be effectively separated from the compressed refrigerant and circulated to and from the rear side of the movable scroll ( 20 ) in order to lubricate moving parts within the compressor ( 1 ) using the refrigerant pressure differentials within the compressor ( 1 ).

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to compressors driven by anelectric motor as the drive source and methods for lubricating movingparts within the compressors.

[0003] 2. Description of Related Art

[0004] Japanese Laid-open Patent Publication No. 5-313156 discloses ageneral scroll compressor that is used as a rotary compressor for an airconditioner, refrigerator, or the like. This scroll compressor isconfigured such that a movable scroll rotates or orbits relative to afixed scroll in order to compress a refrigerant to a high pressurewithin a compression chamber defined between the fixed scroll and themovable scroll. The compressed refrigerant is then discharged from adischarge port defined in the fixed scroll.

[0005] In such a scroll compressor, it would be desirable to supplylubricating oil to portions of a fixed scroll wall that slidably contacta movable scroll wall so as to improve the lubrication of the portionsthat are in sliding contact. However, Japanese Laid-open PatentPublication No. 5-313156 does not suggest any specific technique forsupplying lubricating oil to these portions of the fixed scroll wall andthe movable scroll wall.

SUMMARY OF THE INVENTION

[0006] Therefore, it is one object of the present teachings to providetechniques for effectively supplying lubrication oil to portions of ascroll type compressor that are in sliding contact. Preferably, thescroll type compressor is driven by an electric motor, which drives arefrigerant compression mechanism that discharges compressed refrigerantthrough the fixed scroll.

[0007] According to one aspect of the present teachings, scroll typecompressors are taught that enable lubrication oil to be readilytransferred from a refrigerant discharge side of the compressor toportions of the scroll walls of the fixed and movable scrolls that arein sliding contact by utilizing differences in refrigerant pressurewithin the compressor.

[0008] According to another aspect of the present teachings, scrollcompressors are taught that include a fixed scroll and a movable scroll,each having an opposing scroll wall. A compression chamber may bedefined between the opposing walls of the fixed scroll and the movablescroll. The fixed scroll preferably includes a discharge port ordischarge region for discharging compressed refrigerant from thecompression chamber. An electric motor may drive the movable scroll viaa drive shaft, so that the refrigerant is drawn into the compressionchamber from a suction side or suction port of the compressor. As themovable scroll rotates or orbits relative to the fixed scroll, therefrigerant is then compressed to generate pressurized refrigerantwithin the compression chamber and then the compressed or pressurizedrefrigerant is discharged through the fixed scroll. More specifically,when the movable scroll rotates or orbits relative to the fixed scroll,the respective scroll walls partially slidably contact each other andpreferably lubricating oil is reliably supplied to these portions of thescroll walls that are in sliding contact. Further, the motor optionallymay be disposed within a substantially sealed motor chamber.

[0009] A refrigerant flow channel may be defined from a suction side orsuction port of the compressor through the compression chamber to adischarge side or discharge port of the compressor and the refrigerantpreferably flows from the suction side to the discharge side via therefrigerant flow channel. A communication path or passage optionally maybe provided to enable the refrigerant flow channel to communicate withthe motor chamber. In this case, a so-called “stagnated state” may becreated within the motor chamber. Consequently, a portion of therefrigerant moving through the refrigerant flow channel will reach a“stagnated state” within the motor chamber. Moreover, if a pressuredifference exists between the refrigerant flow channel and the motorchamber, the refrigerant will move so as to equalize the pressuredifference. In this case, heat transfer occurs between the refrigerantwithin the refrigerant flow channel and the refrigerant within the motorchamber, thereby cooling the electric motor disposed inside the motorchamber. During this process, the amount of refrigerant that serves tocool the electric motor is only a small portion of the total amount ofrefrigerant that is moving through the refrigerant flow channel. Thus,this technique has little effect on the compression work being performedby the compressor.

[0010] The scroll type compressor may further include a lubricating oilsupply route. The lubricating oil supply route may serve to supplylubricating oil, which lubricating oil has been discharged to thedischarge area, to the slide contact surfaces of the scroll walls of thefixed and movable scrolls due to difference in pressure between thedischarged refrigerant and an area proximal to the slide contactportions. Preferably, the lubricating oil discharged through the fixedscroll may be separated from the compressor refrigerant by an oilseparator. Because the pressure of the lubricating oil in the dischargedrefrigerant is higher than the pressure around the slide contactportions, the lubricating oil in the discharged refrigerant may beeasily supplied to the slide contact portions due to this difference inpressure by causing the discharge side region to communicate with thearea proximal to the slide contact portions. In addition, thelubricating oil thus supplied to the slide contact portions may be usedto improve the lubricating characteristics of the slide contact portionsand the sealing performance.

[0011] According to another aspect of the present teachings, thelubricating oil supply route may include a first oil supply route and asecond oil supply route. The first oil supply route may supply thelubricating oil to a front side of the movable scroll. Preferably, thefirst oil supply route may be formed in an end portion of a movablescroll substrate that opposes a fixed scroll substrate. The second oilsupply route may transfer the lubricating oil, which has been suppliedto the front side of the movable scroll, to the slide contact portions.The first oil supply route and the second oil supply route may bepositioned so as to correspond to each other, so that the lubricatingoil in the discharge region may be transferred to the slide contactportions via the first and second oil supply routes. Therefore, thesupply of the lubricating oil to the slide contact portions may beachieved by the first and second oil supply routes, which may havesimple configurations.

[0012] In another aspect of the present teachings, methods forcirculating the lubricating oil within electrically driven compressorsare taught and may include supplying the lubricating oil, whichlubricating oil has been discharged to a discharge area, to the slidecontact surfaces of the scroll walls of the fixed and movable scrollsdue to difference in pressure between the discharged refrigerant and thearea proximal to the slide contact surfaces.

[0013] In another aspect of the present teachings, compressorsoptionally may include an oil storage area for storing the lubricatingoil that has been transferred to the slide contact portions via thelubricating oil supply route. In other words, this oil storage area maybe a region or space for storing the lubricating oil that has been usedto lubricate the slide contact portions or the excess lubricating oilthat has been supplied to the slide contact portions. This oil storagearea preferably may be provided, e.g., on the bottom of the motorchamber. In that case, the lubricating oil that has fallen from theslide contact portions toward the bottom of the motor chamber due togravity can be stored in the oil storage area, which may have arelatively simple configuration. Furthermore, the lubricating oil thathas been stored in the oil storage area can be reliably transferred tothe suction-side region via a lubricating oil transfer route. Therefore,the lubricating oil can be reliably circulated using a relatively simpleconfiguration.

[0014] In another aspect of the present teachings, methods are taughtfor circulating lubricating oil through an electrically drivencompressor. Such methods may include circulating lubricating oil bysupplying the lubricating oil from the discharge-side region of thecompressor to the slide contact portions, then transferring thelubricating oil to the suction-side region of the compressor, andfinally returning the lubricating oil to the discharge-side regionagain. These operations may be all performed using the pressuredifferences in the refrigerant along the refrigerant flow path or route.Therefore, the lubricating oil can be easily circulated usingdifferences in refrigerant pressure.

[0015] Such methods may preferably further include storing thelubricating oil before it is transferred from the bearing mechanismregion to the suction-side region. Then, the stored lubricating oil maybe transferred from the bearing mechanism region to the suction-sideregion. Therefore, the lubricating oil can be reliably circulated usingsuch methods.

[0016] Additional objects, features and advantages of the presentinvention will be readily understood after reading the followingdetailed description together with the accompanying drawings and theclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a vertical cross-sectional diagram of a representativescroll compressor.

[0018]FIG. 2 is a perspective diagram taken along line II-II in FIG. 1.

[0019]FIGS. 3 and 4 are partial cross-sectional diagrams illustratingthe relative positions between the first and second oil routes atdifferent rotational positions of a movable scroll.

DETAILED DESCRIPTION OF THE INVENTION

[0020] In one embodiment of the present teachings, electrically drivencompressors may include a fixed scroll and a movable scroll thatarranged and constructed to draw in a refrigerant (or cooling medium orrefrigerant), compress and highly pressurize the refrigerant, and thendischarge the pressurized refrigerant via the fixed scroll. Thecompressor preferably includes a drive shaft, which is coupled to themovable scroll, and an electric motor rotatably driving the drive shaft.The electric motor may be housed within a substantially sealed motorchamber. A bearing may rotatably support the drive shaft. A refrigerantflow channel preferably leads from a suction side of the compressor to adischarge side of the compressor. A communication path (connectingpassage) preferably links the refrigerant flow channel to the motorchamber. A lubricating oil supply route may be defined between adischarge-side region of the refrigerant flow channel and portions ofthe fixed scroll and the movable that slidingly contact each otherduring operation. Preferably, a difference between the pressure at thedischarge-side region of the refrigerant flow channel and at the areaproximal to the slide contact portions causes the lubricating oil to besupplied to the slide contact portions via the lubricating oil supplyroute. A lubricating oil transfer route optionally may be definedbetween the slide contact portions and a suction-side region of therefrigerant flow channel. Preferably, a difference between the pressureat the area proximal to the slide contact portions and the suction-sideregion of the compressor causes the lubricating oil, which waspreviously supplied to the slide contact portions, to be transferred tothe suction-side region. Optionally, a storage area may be provided tostore lubricating oil that has lubricated the slide contact portionsbefore that lubricating oil is transferred via the lubricating oiltransfer route to the suction-side region of the compressor.

[0021] In another embodiment of the present teachings, methods forcirculating lubricating oil through electrically driven compressors aretaught. Such methods may include supplying lubricating oil to slidecontact portions of the fixed scroll and the movable scroll based upon adifference between the pressure at a discharge-side region of arefrigerant flow channel and the pressure at the area proximal to theslide contact portions. Further, the lubricating oil that has lubricatedthe bearing optionally may be transferred to the suction-side region ofthe compressor based upon a difference between the pressure at the areaproximal to the slide contact portions and the suction-side region. Inaddition, after transferring the lubricating oil to the suction-sideregion of the compressor, the lubricating oil optionally may be returnedto the discharge-side region of the compressor due to refrigerantcompression operation being performed by the compression mechanism.Optionally, after lubricating the slide contact portions, thelubricating oil may be temporarily stored in an oil storage area that isdefined proximal to the slide contact portions.

[0022] Each of the additional features and teachings disclosed above andbelow may be utilized separately or in conjunction with other featuresand teachings to provide improved compressors and methods for designingand using such compressors. A representative example of the presentinvention, which example utilizes many of these additional features andteachings both separately and in conjunction, will now be described indetail with reference to the attached drawings. This detaileddescription is merely intended to teach a person of skill in the artfurther details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention. Onlythe claims define the scope of the claimed invention. Therefore,combinations of features and steps disclosed in the following detaildescription may not be necessary to practice the invention in thebroadest sense, and are instead taught merely to particularly describerepresentative examples of the invention. Moreover, various features ofthe representative example and the dependent claims may be combined inways that are not specifically enumerated in order to provide additionaluseful embodiments of the present teachings.

[0023] The representative embodiment of the present teachings will beapplied to a scroll compressor that raises the pressure of theintroduced refrigerant by compressing it within a compression chamberthat is defined between a fixed scroll and a movable scroll. Therefrigerant is then discharged as compressed refrigerant. Lubricatingoil is compressed with the refrigerant and also discharged with thecompressed refrigerant.

[0024] A vertical cross section of the representative electricallydriven scroll compressor 1 is shown in FIG. 1. Generally speaking, thecompressor 1 includes a fixed scroll member 2, a center housing 4, afront housing 5, and a motor housing 6. These structures generallydefine the compressor main body. In FIG. 1, the left-side end face ofcenter housing 4 is coupled to the right-side end face of fixed scrollmember 2. The motor housing 6 is coupled to the right-side end face ofthe center housing 4. The front housing 5 is coupled to the left-sideend face of the fixed scroll member 2. A drive shaft 8 is rotatablysupported by the center housing 4 and the motor housing 6 via radialbearings 10 and 12. An eccentric (or offset) shaft 14, which iseccentric or offset relative to a drive shaft 8, is integrally formed onthe end of the drive shaft 8 on the side of the center housing 4 (theleft side in FIG. 1).

[0025] A bushing 16 is fitted onto the eccentric shaft 14 so as tointegrally rotate with the eccentric shaft 14. A balancing weight 18 isdisposed on the right-side end perimeter of the bushing 16, as shown inFIG. 1, so as to integrally rotate with the bushing 16. A movable scroll20 is supported on the left-side periphery of the bushing 16 by a needlebearing 22 so as to face the fixed scroll 2 and rotate or orbit relativeto the fixed scroll 2. The fixed scroll member 2 and the movable scroll20 basically define a compression mechanism 21 for compressing arefrigerant. The movable scroll 20 has a platter-shaped substrate 24. Acylindrical boss 24 a is disposed so as to protrude or project from theright-side surface of this substrate 24, as shown in FIG. 1. The needlebearing 22 and the radial bearing 10 generally define a bearingmechanism 23 of the movable scroll 20.

[0026] The fixed scroll member 2 includes a platter-shaped substrate 26.A spiral-shaped, e.g., involute-shaped, fixed scroll wall (lap) 28 isdisposed so as to protrude or project from the right-side surface ofthis substrate 26, as shown in FIG. 1. Likewise, a spiral-shaped (e.g.,involute-shaped) movable scroll wall (lap) 30 is disposed so as toprotrude or project from the left-side surface of the substrate 24 ofthe movable scroll 20, as shown in FIG. 1. These scrolls 2 and 20 arepreferably positioned such that the scroll walls 28 and 30 engage eachother.

[0027] Thus, the substrate 26 and fixed scroll wall 28 of the fixedscroll 2 together with the substrate 24 and the movable scroll wall 30of the movable scroll 20 define a crescent-shaped compression chamber(sealed space) 32. More specifically, portions of the fixed scroll wall28 slidingly contact portions of the movable scroll wall 30 at aplurality of sliding contact areas or points (hereinafter “slide contactportions”). The movable scroll 20 revolves or orbits as the eccentricshaft 14 rotates. During this rotating or orbiting movement, thebalancing weight 18 cancels the centrifugal force accompanying therevolution of the movable scroll 20. The eccentric shaft 14 rotatesintegrally with the drive shaft 8, the bushing 16 and the needle bearing22, which are disposed between the eccentric shaft 14 and the boss 24 aof the movable scroll 20. The eccentric shaft 14 is designed to transmitthe rotational force of the drive shaft 8 to the movable scroll 20 asorbiting movement.

[0028] A plurality of (e.g., four) concave areas 34 are defined on thesame circumferential line at uniform angular intervals on the left-sideend face of the center housing 4, as shown in FIG. 1. A fixed pin 36 issecured to the center housing 4 and a movable pin 38 is secured to thesubstrate 24 of the movable scroll 20. The fixed pin 36 and the movablepin 38 are inserted into a concave area 34 and fastened. As theeccentric shaft 14 rotates, self-rotation of the movable scroll 20 isprevented by the concave areas 34, fixed pin 36, and movable pin 38. Inother words, the concave areas 34, fixed pin 36, and movable pin 38 maydefine a self-rotation prevention mechanism for the movable scroll 20.

[0029] The substrate 26 of the fixed scroll 2 may include a reed-typedischarge valve 52, which opens and closes a discharge opening 50. Thisdischarge valve 52 has a reed valve member 54, which has a shape thatcorresponds to the discharge opening 50, and a valve retainer 56 forholding or retaining this reed valve member 54. The reed valve member 54and the valve retainer 56 are secured to the substrate 26 of the fixedscroll 2 by means of a securing bolt 58. The discharge valve 52 isdisposed within a discharge chamber 25 partially defined by thesubstrate 26 of the fixed scroll 2. Preferably, the reed valve member 54opens and closes according to the difference in pressure between thecompression chamber 32, which communicates with the discharge opening50, and the discharge chamber 25. That is, when the pressure in thecompression chamber 32 is higher than the pressure in the dischargechamber 25, the reed valve member 54 opens. Naturally, when the pressurein the compression chamber 32 is lower than the pressure in thedischarge chamber 25, the reed valve member 54 closes. The valveretainer 56 is configured to regulate the maximum opening of the reedvalve member 54.

[0030] An electric motor 49 is disposed within the motor housing 6. Aninverter 60 for controlling the operation of the electric motor 49 isinstalled on the periphery of the housing of the compressor main body,which essentially consists of the fixed scroll 2, center housing 4, andmotor housing 6. The inverter 60 may include, e.g., a switching element62 that generates a relatively large amount of heat, and a condenser 64that generates a relatively small amount of heat. The inverter 60 alsomay include an inverter case 70 for housing these configurationcomponents in order to separate the high and low heat-generatingcomponents from each other. The inverter case 70 preferably contains acylinder 70 a, and the switching element 62 may be disposed on theperiphery of this cylinder 70 a. The inverter case 70 also may include asubstrate 65 for installing the condenser 64. The cylinder 70 a ofinverter case 70 preferably communicates with a suction port 44. One endof the suction port 44 preferably communicates with the fixed scroll 2while the other end of the suction port 44 preferably communicates witha refrigerant feedback pipe (not shown) of an external circuit.

[0031] The switching element 62 of the inverter case 70 may beelectrically coupled to the electric motor 49 by means of threeconducting pins 66 (only one of which is shown in the figure) andconductive wires 67 and 68. The conducting pins 66 preferably penetrateinto the motor housing 6 and the inverter case 70. Electric currentnecessary for driving the electric motor 49 is supplied via theseconducting pins 66 and conductive wires 67 and 68.

[0032] The location for connecting the conductive wire 68 with thestator coil 46 a of the electric motor 49, which will be furtherdescribed below, is preferably provided on the side of the electricmotor 49 that faces the compressor mechanism 21. The inverter 60 issecured to the compressor housing (e.g., the center housing 4 and/or themotor housing 6). The location for connecting the electric motor 49 withthe inverter 60 is preferably provided on the periphery of the casingalong its diametric direction. In other words, this configurationproduces a compact design with a much shorter axial length than aconfiguration in which the inverter (or a similar device) is disposed onthe periphery along the axial direction. Moreover, the location forconnecting the electric motor 49 with the inverter 60 is provided suchthat these components are close to each other. As a result, because theelectric motor 49 can be connected to the inverter 60 over the shortestdistance possible, a short connection member can be used. Consequently,material cost and weight can be reduced, and performance can be improvedby minimizing voltage drops across the connection member.

[0033] A stator 46 is secured to the inner surface of the motor housing6 and a rotor 48 is secured to the drive shaft 8. The drive shaft 8,stator 46, and rotor 48 generally define the electric motor 49. Thestator 46 has a stator coil 46 a, and by applying electric current tothis stator coil 46 a, the rotor 48 and drive shaft 8 rotate together.The electric motor 49 is preferably disposed within a substantiallysealed motor chamber 45, which is defined within the motor housing 6 andcenter housing 4.

[0034] As the eccentric shaft 14 of the drive shaft 8 rotates, themovable scroll 20 revolves (orbits), and the refrigerant introduced fromthe suction port 44 (which is defined within the fixed scroll 2) flowsinto the space between the substrate 26 of the fixed scroll 2 and thesubstrate 24 of the movable scroll 20 from the edge of both scrolls 2and 20. As the movable scroll 20 revolves, the movable pin 38 slidesalong the circumferential (peripheral) surface of the fixed pin 36.Then, when the eccentric shaft 14 further rotates, the movable scroll20, which is installed on said eccentric shaft 14 via the needle bearing22 so as to be able to rotate relative to the eccentric shaft 14,revolves around the central axis of the drive shaft 8 without rotatingitself. As the movable scroll 20 revolves, the refrigerant that has beenintroduced through the suction port 44 flows into the compressionchamber 32 and is guided to the center of the fixed scroll 2 while itspressure increases. Then, the pressurized (compressed) refrigerant flowsinto the discharge opening 50 that is defined in the center of thesubstrate 26 of the fixed scroll 2. That is, the discharge opening 50communicates with the compression chamber 32 where the pressure reachesits highest value.

[0035] The center housing 4, which separates the compression mechanism21 from the motor chamber 45, preferably includes a connecting passage47. This connecting passage 47 may serve to connect the suction regionwithin the refrigerant flow channel, which is defined within thecompression mechanism 21 and leads from the suction port 44 to thedischarge port 86, to the motor chamber 45. In other words, the openingthrough which the refrigerant enters communicates with the space 47 aformed between the peripheral surface of the substrate 24 of the movablescroll 20 and the internal wall surface of the scroll-housing space forhousing said substrate 24. The space 47 a communicates with the motorchamber 45 via a communication hole 47 b, which is defined in the centerhousing 4. Thus, the space 47 a and the communication hole 47 bgenerally define the connecting passage 47.

[0036] While the compressor 1 is operating, the connecting passage 47always communicates with the refrigerant flow channel regardless of theposition of the substrate 24 of the movable scroll 20, which revolvesinside the scroll-housing space. Consequently, heat is transferred viathe connecting passage 47 between the refrigerant introduced into therefrigerant flow channel and the refrigerant disposed within the motorchamber 45. That is, heat moves from the motor chamber 45, which is at ahigher temperature, to the refrigerant flow channel, and this heattransfer cools the electric motor 49. Moreover, when a pressuredifference occurs between the motor chamber 45 and the refrigerantsuction region, refrigerant will flow between the motor chamber 45 andthe suction region via the connecting passage 47 so as to equalize thepressure difference. Therefore, heat is transferred along with thisrefrigerant flow, and as a result, the electric motor 49 is cooled.Accordingly, the electric motor 49 is prevented from overheating.

[0037] Unlike known methods that utilize the motor chamber as therefrigerant channel, the present cooling methods and apparatus are basedon so-called “stagnation cooling,” which is not accompanied by a largerefrigerant flow. The introduced refrigerant directly involved in thistype of “stagnation cooling” is only a small portion of the totalintroduced refrigerant flowing through the refrigerant flow channel.Thus, the introduced refrigerant does not significantly raise orincrease the temperature of the total introduced refrigerant. Therefore,an increase in the specific volume of the introduced refrigerant can beprevented, thereby eliminating the problem of reduced compressionefficiency. Although the present embodiment uses a configuration inwhich the inverter 60 is cooled by the introduced refrigerant, theamount of heat generated by the inverter 60 is much less compared to theamount of heat that is generated by the electric motor 49. Therefore,the rise in the temperature of the introduced refrigerant caused bycooling the inverter 60 using said introduced refrigerant is smallcompared to the temperature rise that would be caused by cooling theelectric motor 49 if all of the introduced refrigerant is supplied intothe motor chamber 45. Therefore, compression efficiency is not reduced.

[0038] Moreover, in the present embodiment, because a low-temperatureintroduced refrigerant cools the electric motor 49, an improved coolingeffect can be obtained than when using discharged refrigerant to coolthe electric motor 49. Furthermore, the present configuration, whichguides the introduced refrigerant to the motor chamber 45, does notrequire a sealing material to be disposed around the drive shaft 8,which drive shaft 8 transmits the drive force of the electric motor 49to the compression mechanism 21. Therefore, a simple structure can bemanufactured at a reduced cost.

[0039] The front housing 5 may include an oil separator 80 forseparating the lubricating oil within the refrigerant that has beendischarged from the discharge chamber 25. This oil separator 80 mayutilize, e.g., a separation mechanism that relies upon centrifugal forceto perform the oil separation. Thus, the oil separator 80 may generallyinclude an oil separation chamber 81, a cylindrical member 82, a filter84 installed below the cylindrical member 82, and a storage area(lubricating oil reservoir) 85 for temporarily storing the separatedlubricating oil. A connection hole or passage 83 may be defined betweenthe oil separation chamber 81 and the storage area 85 in order to allowlubricating oil to pass from the oil separation chamber 81 to thestorage area 85. When the compressed refrigerant discharged from thedischarge chamber 25 is introduced into the oil separator 80, asindicated by the curved, solid-line arrow in FIG. 1, the compressedrefrigerant collides with the cylindrical member 82 in the oilseparation chamber 81 and descends while circling around the cylindricalmember 82. Therefore, the lubricating oil contained in the compressedrefrigerant will separate due to centrifugal force and the lubricationoil will move, due to gravity, as indicated by the dotted-line arrowshown in FIG. 1.

[0040] Then, after the lubricating oil passes through the connectionhole 83 and filter 84, the lubricating oil may be temporarily stored inthe storage area 85. Meanwhile, the discharged refrigerant (from whichthe lubricating oil has been separated) moves from the opening 82 a ofthe cylindrical member 82 to a discharge port 86, and then istransferred to a condenser (not shown) in an external circuit.

[0041] A gasket 90 is preferably disposed between the right end face ofthe front housing 5 and the left end face of the fixed scroll 2. Asshown in FIG. 2, a first oil supply hole 91, which communicates with thestorage area 85, is defined near the bottom of this gasket 90, and asecond oil supply hole 93 is defined near the top of the gasket 90. Thefirst and second oil supply holes 91, 93 communicate with each other viaan oil supply groove (lubricating oil supply passage) 92. A first oilsupply route 94 extends from the oil supply hole 93, which is defined atan edge of the fixed scroll substrate 26, to the front side (the leftside of the substrate 24 of the movable scroll 20 in FIG. 1) of themovable scroll 20. The first oil supply route 94 preferably has athrottled shape. That is, the area of its oil flow channel is smaller onthe side of movable scroll 20 than on the side of the fixed scroll 2.Therefore, it is possible to prevent an unnecessary amount oflubricating oil from being supplied through this first oil supply route94.

[0042] In addition, as shown in FIGS. 1, 3 and 4, a second oil supplyroute 95 for communicating lubricating oil may be defined on the frontportion of the movable scroll 20 (left side of the movable scroll 20 asviewed in FIG. 1) that corresponds to the first oil supply route 94. Thesecond oil supply route 95 may include a concave area 95 a. The secondoil supply route 95 may connect the first oil supply route 94 and anarea proximal to the slide contact portions of the scroll walls 28 and30. Therefore, the storage area 85 of the front housing 5 communicateswith the area (peripheral area) proximal to the slide contact portionsof the scroll walls 28 and 30 via the second oil supply route 95, theoil supply holes 91 and 93, and the lubricating oil supply route, whichincludes the oil supply groove 92 and the first oil supply route 94.

[0043] Because the second oil supply route 95 is defined on the movablescroll substrate 24, the position of the second oil supply route 95relative to the first oil supply route 94 changes as the movable scroll20 rotates. Consequently, the concave area 95 a of the second oil supplyroute 95 may be configured to always communicate with the first oilsupply route 94 regardless of the rotational position of the movablescroll 20.

[0044] The storage area 85, which is at the discharge pressure, has ahigher pressure than the peripheral area proximal to the slide contactportions. Consequently, the lubricating oil L stored in the storage area85 is force-fed by the pressure difference to the slide contact portionsvia the lubricating oil supply route 91-95. The lubricating oil L storedin the storage area 85 will hereinafter be referred to as “thelubricating oil in the discharge-side region.”

[0045] Next, changes in position of the second oil supply route 95relative to the first oil supply route 94 and resulting changes in theflow of the lubricating oil during this process will be explained withreference to FIGS. 3 and 4.

[0046] The revolving motions of the movable scroll 20 can be expressedas vertical reciprocal movements with respect to FIG. 1. That is, whilerevolving, the movable scroll 20 is disposed in the position shown inFIG. 3 or FIG. 4. In the position shown in FIG. 3, the first oil supplyroute 94 communicates with concave area 95 a of the second oil supplyroute 95. However, the lubricating oil L that has entered the concavearea 95 a may be supplied to the outside of the concave area onlythrough an extremely minute clearance between the fixed scroll 2 and themovable scroll 20. Therefore, the lubricating oil L will not bepositively supplied to the slide contact portions of the fixed scroll 2and the movable scroll 20.

[0047] In the position shown in FIG. 4, the first oil supply route 94communicates with the concave area 95 a of the second oil supply route95, while a refrigerant flow channel is defined between the fixed scroll2 and the movable scroll wall 30. Therefore, almost of the lubricatingoil, which has been supplied from the first oil supply route 94 to thefront side of the movable scroll substrate 24, may be supplied to theslide contact portions of the fixed scroll 2 and the movable scroll 20via the concave area 95 a of the second oil supply route 95. As aresult, the lubricating oil can lubricate the slide contact portions andimprove sealing performance.

[0048] Meanwhile, a small amount of the lubricating oil that hassupplied to the front side of the movable scroll substrate 24 may alsobe supplied to the back side (right side as viewed in FIG. 1) of themovable scroll 20, so that the lubricating oil can lubricate the bearingmechanism 23. The lubricating oil may then fall due to gravity from thebearing mechanism 23 and may be stored in a storage area 45 a (concavearea) formed on the bottom of the motor chamber 45.

[0049] A transfer route 4 a (hereinafter referred to as “the lubricatingoil transfer route”) may preferably defined in the lower portion (onelocation) of the center housing 4, which corresponds to the storage area45 a. This transfer route 4 a links the storage area 45 a of the motorchamber 45 to the suction region (hereafter also referred to as “thesuction-side region”) of the compression mechanism 21. When thelubricating oil in the storage area 85 is being supplied to the rearside of the movable scroll 20, a portion of the discharged refrigerantis also carried along through the lubricating oil supply route 91-95.Consequently, the pressure in the storage area 45 a becomes higher thanthe pressure in the suction region, which is at the introducedrefrigerant pressure. Lubricating oil L that has lubricated the slidecontact portions of the fixed and movable scrolls 2, 20 may fall intothe storage area 45 a for temporary storage.

[0050] Thereafter, the lubricating oil L, which has been temporarilystored in the storage area 45 a, is transferred by the pressuredifference to the suction side region or the suction port 44 of thecompression mechanism 21 via the transfer route 4 a. Then, thislubricating oil L is transferred from the discharge opening 50 to theoil separator 80, together with the refrigerant that has been highlypressurized in the compression chamber 32, and is discharged. Thus, inthe above representative embodiment, the first oil supply hole 91 mayserve as a first end of the lubricating oil supply route 91-95, whichfirst end communicates with the discharge port 86 (the discharge sideregion), while the second oil supply route 95 may serve as a second endof the lubricating oil supply route 91-95, which second end communicateswith the suction port 44 (the suction side region). The lubricating oilL contained in the discharged refrigerant is again separated by the oilseparator 80 and force-fed to the rear side of the movable scroll 20 viathe lubricating oil supply route 91-95. In this way, the lubricating oilcontained in the discharged refrigerant is circulated to and from therear side of the movable scroll 20. The capacity of the storage area 45a and the size of the flow channel area of the transfer route 4 a, etc.can be appropriately set according to the volume of lubricating oil Lthat will be stored in the storage area 45 a.

[0051] In the scroll compressor having the above-describedconfiguration, when the electric motor 49 is driven, the refrigerantreturning from the evaporator (not shown) of an external circuit isguided into the compressor 1 via the cylinder 70 a and suction port 44.During this process, the refrigerant passing through the cylinder 70 acools the inverter 60. Then, this refrigerant is highly pressurized inthe compression chamber 32 as the movable scroll 20 revolves, and isthen transferred as discharged refrigerant to the condenser (not shown)of an external circuit from the discharge port 86.

[0052] As described above, the lubrication oil L may be rationally usedfor lubrication, because the lubricating oil L has been separated fromdischarged refrigerant at the discharge region by means of the oilseparator 80. Moreover, the lubricating oil L can be readily transferredwithin the compressor 1 by utilizing pressure differences of therefrigerant disposed within the compressor 1. Furthermore, because thelubricating oil L is supplied to the slide contact portions of thescroll walls 28 and 29 of the fixed and movable scrolls 2 and 20,respectively, via the lubricating oil supply route (i.e., the oil supplyholes 91 and 93, oil supply groove 92, first oil supply route 94, andsecond oil supply route 95), the lubricating characteristics anddurability of the bearing mechanism 23 can be improved.

[0053] The present invention is not limited to the above embodiment, andvarious kinds of applications and modifications are possible. Forexample, the above embodiment modified in the following ways:

[0054] (A) In the above representative embodiment, the lubricating oil Lthat has been separated from the discharged refrigerant by the oilseparator 80 is supplied to the slide contact portions of the scrollwalls 28, 30 of the fixed and movable scrolls 2, 20. However, it is alsopossible to use, for example, a configuration in which the lubricatingoil L stored in a storage area, which is different from the oilseparator 80, is supplied to the slide contact portions using thedifference in pressure between the discharged refrigerant and the regionproximal to the slide contact portions.

[0055] (B) In the above representative embodiment, the second oil supplyroute 95 is defined within the movable scroll 20. However, the oilsupply route 95 may be defined in the fixed scroll 2 in a positioncorresponding to the first oil supply route 94.

1. A scroll compressor comprising: a fixed scroll and a movable scrollhaving respective scroll walls, the scroll walls slidably contactingeach other and defining a compression chamber between the fixed scrolland the movable scroll, an electric motor rotatably driving the movablescroll, whereby a refrigerant is drawn from a suction-side region, iscompressed within the compression chamber and is then discharged to adischarge-side region as the movable scroll rotates relative to thefixed scroll, wherein a refrigerant flow channel is defined from thesuction side region to the discharge side region via the compressionchamber, a motor housing defining a substantially sealed motor chamber,wherein the electric motor is disposed within the motor chamber, acommunication path linking the refrigerant flow channel to the motorchamber and a lubricating oil supply route defined between adischarge-side region of the refrigerant flow channel and an areaproximal to slide contact portions of the scroll walls of the fixed andmovable scrolls, the lubricating oil supply route being arranged andconstructed so that a difference between the pressure at thedischarge-side region of the refrigerant flow channel and the pressureat the area proximal to the slide contact portions of the scroll wallsof the fixed and movable scrolls urges lubricating oil towards the slidecontact portions of the scroll walls of the fixed and movable scrollsvia the lubricating oil supply route.
 2. A scroll compressor as in claim1, wherein the lubricating oil supply route includes a first oil supplyroute and a second oil supply route, the first oil supply routesupplying the lubricating oil to a front side of the movable scroll, andthe second oil supply route communicating with the front side of themovable scroll and extending to the slide contact portions.
 3. A methodfor circulating lubricating oil through an electric compressor having afixed scroll and a movable scroll with respective scroll walls thatslidably contact with each other and define a compression chamberbetween the fixed scroll and the movable scroll, wherein a refrigerantflow channel is defined between a suction-side region and adischarge-side region, and a lubricating oil supply route is definedbetween the discharge-side region of the refrigerant flow channel andthe area proximal to slide contact portions of the scroll walls of thefixed and movable scrolls, comprising: pressure-feeding lubricating oilto the slide contact portions of the scroll walls of the fixed andmovable scrolls via the lubricating oil supply route based upon adifference between the pressure at the discharge-side region of therefrigerant flow channel and the pressure at the area proximal to theslide contact portions of the scroll walls of the fixed and movablescrolls.
 4. A method as in claim 3, wherein the lubricating oil supplyroute includes a first oil supply route and a second oil supply route,the method further comprising supplying lubricating oil via the firstoil supply route to a front side of the movable scroll, and supplyinglubricating oil via the second oil supply route to the slide contactportions of the scroll walls of the fixed and movable scrolls.
 5. Ascroll compressor comprising: a compressor having a fixed scroll and amovable scroll, the movable scroll coupled to a drive shaft, wherein adischarge-side region is disposed in communication with the fixedscroll, an electric motor rotatably driving the drive shaft, and alubricating oil route arranged and constructed to transfer lubricationoil from the discharge-side region to slide contact portions of thefixed and movable scrolls via the lubricating oil supply route so as tolubricate the slide contact portions as the refrigerant is compressed bythe compressor.
 6. A scroll compressor as in claim 5, wherein thelubricating oil route has a first end and a second end that respectivelycommunicate with the discharge-side region and a suction-side region ofthe compressor, wherein the lubricating oil route is arranged andconstructed so that the lubrication oil flows from the discharge-sideregion to the slide contact portions of the fixed and movable scrollsdue to a difference in pressure between refrigerant pressure at thedischarge-side region and refrigerant pressure at an area proximal tothe slide contact portions of the fixed and movable scrolls.
 7. A scrollcompressor as in claim 6, further including an oil separatorcommunicating with the discharge-side region, the oil separator beingarranged and constructed to separate the lubricating oil from compressedrefrigerant that has been discharged from the compression chamber.
 8. Amethod for circulating lubricating oil within an electrically drivenscroll compressor driven by an electric motor, the method comprising:generating a pressure differential between a discharge-side region ofthe compressor and slide contact portions of the compressor, therebycausing lubricating oil to move via a lubricating oil route from thedischarge-side region to the slide contact portions.
 9. A method as inclaim 8, wherein the pressure differential along the lubricating oilroute is generated due to refrigerant that is compressed by thecompressor.
 10. A method as in claim 9, wherein a first end of thelubricating oil route communicates with the discharge-side region and asecond end of the lubricating oil route communicates with a suctionport, the method further comprising forcing the lubrication oil from thedischarge-side region to the area proximal to the slide contact portionsdue to a difference in refrigerant pressure between the discharge-sideregion and the area proximal to the slide contact portions.
 11. Anmethod as in claim 10, further comprising pressure-feeding thelubricating oil via a lubricating oil transfer route defined between thearea proximal to the slide contact portions and the suction-side regionof the compressor due to a difference between the refrigerant pressureat the area proximal to the slide contact portions and the suction-sideregion of the compressor.
 12. A method as in claim 11, further includingseparating the lubricating oil from compressed refrigerant that has beendischarged from a compression chamber of the compressor.
 13. A method asin claim 12, further including storing the lubricating oil thatlubricated the slide contact portions before the stored lubricating oilis transferred to the suction-side region.
 14. A method for circulatinglubricating oil within an electrically driven scroll compressor,comprising: separating lubricating oil from compressed refrigerant in anarea proximal to and communicating with a discharge port of thecompressor, and transferring the separated lubricating oil to slidecontact portions of scroll walls of fixed and movable scrolls via alubricating oil supply route using a refrigerant pressure-differentialbetween the area proximal to and communicating with the discharge portand an area proximal to the slide contact portions of the scroll wallsof the fixed and movable scrolls, wherein the slide contact portions arelubricated with the lubricating oil .
 15. An electrically driven scrollcompressor, comprising: means for separating lubricating oil fromcompressed refrigerant in an area proximal to and communicating with adischarge port of the compressor, and means for transferring theseparated lubricating oil to slide contact portions of scroll walls offixed and movable scrolls using a refrigerant pressure-differentialbetween the area proximal to and communicating with the discharge portand an area proximal to the slide contact portions of the scroll wallsof the fixed and movable scrolls, whereby the slide contact portions arelubricated with the lubricating oil.